Possible Blown Head Gasket??

[dktmllr]

I did a compression test on my 1991 m42 and got these results and my cousin is telling my I probably blew my head gasket. Any thoughts.


Cylinder 1


Cylinder 2

Cylinder 3

Cylinder 4

[noahds]

No expert here:
But good(high) consistent compression across all cylinders is vindictive of a healthy m42. Yours IMO is fine


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[ThatOneEuroE30]

Dont listen to him. That things fine. All cylinders are within 10% of each other.

[uturn]

What prompted you to do a compression check? What running issues are you having?

[roguetoaster]

I too do not understand why you would think consistent numbers would be indicative of a coolant leak.

Seems to me that you are good to go for bouncing the limiter as much as you want.

[parkerbink]

Gonna need a symptom.

Based on that I'd say you have a happy healthy engine.

[dktmllr]

That's what I was thinking haha he builds evo rally cars so he thinks he know everything haha but the reason I'm wondering is because I just replaced all three of my belts from them popping on the highway while I was driving in about 85° weather which caused a little coolant plastic water pipe connector to burst that comes off the block that runs to the cooling system so I had to replace that and then I had my thermostat replaced my car runs and starts fine and everything I'm just still getting a hot reading my car will get up to operating temperature then it'll fluctuate between the three fourths and the halfway mark but it never gets passed the three fourths mark on my temperature gauge, but I just also noticed I can stop my fan clutch almost always even when my cars up to operating temperature? Any thoughts?

[ThatOneEuroE30]

That's what I was thinking haha he builds evo rally cars so he thinks he know everything haha but the reason I'm wondering is because I just replaced all three of my belts from them popping on the highway while I was driving in about 85° weather which caused a little coolant plastic water pipe connector to burst that comes off the block that runs to the cooling system so I had to replace that and then I had my thermostat replaced my car runs and starts fine and everything I'm just still getting a hot reading my car will get up to operating temperature then it'll fluctuate between the three fourths and the halfway mark but it never gets passed the three fourths mark on my temperature gauge, but I just also noticed I can stop my fan clutch almost always even when my cars up to operating temperature? Any thoughts?

You need to replace the fan clutch and might have some air in the system still. My car would do the same i put in a new clutch in and made sure it was bleed all the way. Haven't had an issue since

[dktmllr]

Thanks for the tips ThatOneEuroE30 it helps a lot man, So how do I bleed the cooling system a couple times to release these air bubbles? And I've just ordered a Mahle-Beth fan clutch off of ECS Tuning as well as the fan clutch pulley tool

[ThatOneEuroE30]

Thanks for the tips ThatOneEuroE30 it helps a lot man, So how do I bleed the cooling system a couple times to release these air bubbles? And I've just ordered a Mahle-Beth fan clutch off of ECS Tuning as well as the fan clutch pulley tool

When i bled my system. I jacked up the front of the car just a couple inches and then there is a bleeder screw on the top of the expansion tank. Just unscrew that a couple threads not all the way out and let the car run up to op temp. I like to blip the throttle a couple times once its up to temp just to ensure I'm working all the bubbles out. Once you do that just let it cool down and check the coolant level to see if it needs some or not.

[TobyB]

my cousin is telling my I probably blew my head gasket

I think he wants a deal on your car.

t

[e30davie]

You can still have good compression and still have a blown headgasket, its possible to blow the gasket out the side of the block or blow between the coolant and oil gallery. I have seen both on various engines over the years, admittedly not on an m42.

Overheating is also not a completely fail safe test for blown gasket either as mentioned by the recommendation to bleed the system.

Also the fan clutch only works when you are not moving. If you are driving constantly, like on the highway you should not have any overheating issues regardless of the condition of the fan clutch. Overheating at idle or stopped but running cool when driving is an indication of a bad clutch fan.

Don't just throw parts at things, figure out the issue then buy parts to fix.

[dktmllr]

You can still have good compression and still have a blown headgasket, its possible to blow the gasket out the side of the block or blow between the coolant and oil gallery. I have seen both on various engines over the years, admittedly not on an m42.

Overheating is also not a completely fail safe test for blown gasket either as mentioned by the recommendation to bleed the system.

Also the fan clutch only works when you are not moving. If you are driving constantly, like on the highway you should not have any overheating issues regardless of the condition of the fan clutch. Overheating at idle or stopped but running cool when driving is an indication of a bad clutch fan.

Don't just throw parts at things, figure out the issue then buy parts to fix.

I appreciate the help man yeah unfortunately this is something I've been dealing with for about a month now and I'm just now narrowing it down to the fan clutch because as you said my car goes back to normal temp which is the halfway point when I'm driving on the highway and when I'm driving the car but when I I'm at an idle that's when it starts fluctuating between a half and 3/4 mark but when I start driving it it'll cool down and it'll get it back to the halfway point, and my catalytic converter is plugged as well so I'm dealing with that too

[e30davie]

..... and my catalytic converter is plugged as well so I'm dealing with that too

Fix this asap.

blocked exhaust = no power and high potential of heat issues as heat cant excape.

[dktmllr]

Fix this asap.

blocked exhaust = no power and high potential of heat issues as heat cant excape.

Yeah I haven't been really driving it for that reason, ordered an aftermarket high flow cat and I'm taking it to an exhaust shop tomorrow to get it all fixed up!
Thank you for all the help man